Iain Henderson makes his first Six Nations start in the back row on Saturday - after Peter O'Mahony failed to prove his fitness.

The 22-year-old Ulsterman replaces Ireland's player of the championship to date in the only change made by Ireland boss Joe Schmidt for the clash with Italy at the Aviva Stadium.

O'Mahony, banged up with hamstring and shoulder problems after Ireland's Twickenham defeat, was deemed too much of a risk.

The Munster captain is given the weekend off as Ireland attempt to keep themselves in pole position, giving Henderson the opening for his ninth Test cap - and only his second Ireland start. But Ireland are boosted by Jonathan Sexton's availability.

The first-choice out-half was a big doubt after injuring his thumb against England, a setback that his club Racing Metro claimed would keep him out for between 10 days and six weeks.

However Schmidt was always confident that the Dubliner would be fit and after coming through training at Carton House this afternoon, he is in the side.

Leinster duo Rhys Ruddock and Jordi Murphy will provide the back row back-up while Paddy Jackson will also cover for Sexton. As expected Brian O'Driscoll starts at centre after shaking off a calf problem and he is poised to make his 140th Test appearance - a world record.